1. Field of the Invention
This invention relates to a photographing apparatus provided with a metering system.
2. Description of the Prior Art
Cameras, cinecameras, video cameras, etc., are known as photographing apparatuses. These photographing apparatuses are provided with a metering system therein for detecting the brightness information of an object to be photographed. FIG. 1 of the accompanying drawings is a view for illustrating the metering system of a conventional single lens reflex type camera. The light beam from the object 1 to be photographed passes through a photo-taking lens system 2, and then is directed to a finder optical system by a reflecting mirror 7 and passes through a focusing screen 6 and a condenser lens 4 in succession, whereafter it is inwardly reflected by a penta prism 3 and directed to the observer 9. In that case, part of the light beam is divided by a half-prism 4a provided in the finder optical path of the condenser lens 4 and is directed to a metering element 5 such as silicon or CdS provided outside the finder optical path. The brightness of the object to be photographed is measured by the output from the metering element 5 and the amount of exposure is determined.
As another example of the conventional measuring system, as shown in FIG. 2 of the accompanying drawings, a part of the reflecting surface of a reflecting mirror 7 is formed by a half-mirror and a metering element 8 is secured to the back of the reflecting mirror 7 at a position for receiving the light beam passed through the half-mirror, whereby the brightness of the object to be photographed is measured.
However, in the metering system shown in FIG. 1, when the object to be photographed is to be observed through the half-prism 4a is directed away from the optical path to the finder and therefore, a dark portion is created in the central portion of the finder. This provides a very great hindrance when the object to be photographed is monitored. Further, the light beam divided by the half-mirror is determined by the shape of the half-mirror. Therefore, the metering system is restricted to one whereby the central portion of the finder picture plane is emphatically metered and to the system whereby the entire picture plane is averagely metered, or the condensor lens must be interchanged if an attempt is made to adopt the respective systems.
Also, in the metering system shown in FIG. 2, a plurality of metering elements are disposed on the back of the reflecting mirror 7, whereby they are suitably selected and it is possible to electrically choose the center priority metering or the average metering. In this system, however, to sufficiently secure the brighness of the image seen from the finder, the half-mirror of the reflecting mirror must be made into a structure of high reflection factor and accordingly, the light passed through the half-mirror and entering the metering element 8 becomes weaker and the metering in a dark environment becomes inaccurate. A further disadvantage of this system is that when the shutter button is depressed and photographing is effected on the film, this reflecting mirror is designed to jump upwardly and therefore the connection for supplying the electrical signal from the metering element to the camera body side is difficult and is lacking reliability.